Re: ATAPI devices in AHCI mode not working

[Tejun Heo <htejun@gmail.com>]

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Gaston, Jason D wrote:
>> -----Original Message-----
>> From: Alan Cox [mailto:alan@lxorguk.ukuu.org.uk]
>> Sent: Monday, October 29, 2007 3:14 PM
>> To: Gaston, Jason D
>> Cc: linux-ide@vger.kernel.org
>> Subject: Re: ATAPI devices in AHCI mode not working
>>
>>> ata1: SATA max UDMA/133 abar m1024@0xd9101000 port 0xd9101100 irq 216
>>> ata2: SATA max UDMA/133 abar m1024@0xd9101000 port 0xd9101180 irq 216
>>> ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
>>> ata1.00: ATAPI: ATAPI   DVD D  DH16D2S, EP52, max UDMA/100
>>> ata1.00: configured for UDMA/100
>> Much better - no misdetected link type, no device claiming to be PATA
>> when its SATA.
>>
>>
>> Right that eliminates all the obvious goings on being caused by broken
>> devices which is a start. Doesn't shed any light on the rest of it.
> What
>> happens if you boot with irqpoll enabled ? (wondering if the timeouts
> are
>> ACPI or IRQ routing stuff)
> 
> I rebuilt the kernel; the DVD and USB devices are functional now. I'm
> not sure what the problem was before.  On a side note: In 2.6.24.rc1 the
> DVD starts working right away, but on a SLES10_SP1 kernel, it takes some
> time for it to step down to a PIO mode before the DVD can be mounted.
> Oh well.

Yeah, there has been quite some update in libata between SLES10_SP1 and
2.6.24-rc1.  The controller being ahci, I wonder whether this is caused
by the different in check_atapi_dma().

1. Does other optical drives have the same problem?  If not, please post
the result of "hdparm -I /dev/sr0" with the problematic one attached.

2. If you apply the attached patch to 2.6.24-rc1, does it behave the
same as the SLES10SP1 kernel?

-- 
tejun

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diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8ee56e5..5d9b193 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4491,11 +4491,13 @@ int ata_check_atapi_dma(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
 
+#if 0
 	/* Don't allow DMA if it isn't multiple of 16 bytes.  Quite a
 	 * few ATAPI devices choke on such DMA requests.
 	 */
 	if (unlikely(qc->nbytes & 15))
 		return 1;
+#endif
 
 	if (ap->ops->check_atapi_dma)
 		return ap->ops->check_atapi_dma(qc);